opensmtpd-filter-sake/src/address.rs

use crate::code::generate_code;
use anyhow::{ensure, Error, Result};
use data_encoding::{BASE32_NOPAD, BASE64};
use std::hash::{Hash, Hasher};
use std::str::FromStr;

#[derive(Clone, Debug, Eq, PartialEq)]
pub struct CodedAddress {
	local_part: String,
	sub_addr: Option<String>,
	code: Vec<u8>,
	domain: Option<String>,
	separator: char,
}

impl CodedAddress {
	pub fn parse(s: &str, separator: char) -> Result<Self> {
		let (local_part, domain) = split_local_part(s);
		ensure!(!local_part.is_empty(), "{s}: local part cannot be empty");
		let domain = domain
			.map(|dom| -> Result<String> {
				ensure!(!dom.is_empty(), "{s}: domain cannot be empty");
				Ok(idna::domain_to_ascii(&dom)?)
			})
			.transpose()?;
		let parts: Vec<&str> = local_part.split(separator).collect();
		let local_part = parts[0].to_string();
		ensure!(!local_part.is_empty(), "{s}: local part cannot be empty");
		let sub_addr = if parts.len() >= 2 {
			Some(parts[1].to_string())
		} else {
			None
		};
		let code = if parts.len() >= 3 {
			BASE32_NOPAD
				.decode(parts[2].to_uppercase().as_bytes())
				.unwrap_or_default()
		} else {
			Vec::new()
		};
		Ok(Self {
			local_part,
			sub_addr,
			code,
			domain,
			separator,
		})
	}
}

#[derive(Clone, Debug)]
pub struct KeyedAddress {
	local_part: String,
	domain: Option<String>,
	key: Vec<u8>,
}

impl KeyedAddress {
	pub fn check_code(&self, addr: &CodedAddress) -> bool {
		if addr.local_part.is_empty() || self.key.is_empty() {
			return false;
		}
		match &addr.sub_addr {
			Some(sub_addr) => {
				if !sub_addr.is_empty() {
					addr.code
						== generate_code(&addr.local_part, addr.separator, sub_addr, &self.key)
				} else {
					false
				}
			}
			None => false,
		}
	}
}

impl PartialEq for KeyedAddress {
	fn eq(&self, other: &Self) -> bool {
		self.local_part == other.local_part && self.domain == other.domain
	}
}

impl PartialEq<CodedAddress> for KeyedAddress {
	fn eq(&self, other: &CodedAddress) -> bool {
		if let Some(domain_k) = &self.domain {
			if let Some(domain_c) = &other.domain {
				if domain_k != domain_c {
					return false;
				}
			}
		}
		self.local_part == other.local_part
	}
}

impl Eq for KeyedAddress {}

impl Hash for KeyedAddress {
	fn hash<H: Hasher>(&self, state: &mut H) {
		self.local_part.hash(state);
		self.domain.hash(state);
	}
}

impl FromStr for KeyedAddress {
	type Err = Error;

	fn from_str(s: &str) -> Result<Self> {
		let ksplit = s.rsplit_once(crate::KEY_SEPARATOR);
		ensure!(ksplit.is_some(), "{s}: key separator not found");
		let (address, key_b64) = ksplit.unwrap();
		let (local_part, domain) = split_local_part(address);
		ensure!(!local_part.is_empty(), "{s}: local part cannot be empty");
		let domain = domain
			.map(|dom| -> Result<String> {
				ensure!(!dom.is_empty(), "{s}: domain cannot be empty");
				Ok(idna::domain_to_ascii(&dom)?)
			})
			.transpose()?;
		let key = BASE64.decode(key_b64.as_bytes())?;
		ensure!(!key.is_empty(), "{s}: key cannot be empty");
		ensure!(
			crate::ALLOWED_KEY_SIZES.contains(&key.len()),
			"{s}: key length must be either 128 or 256 bits"
		);
		Ok(Self {
			local_part,
			domain,
			key,
		})
	}
}

fn split_local_part(s: &str) -> (String, Option<String>) {
	match s.rsplit_once('@') {
		Some((local_part, domain)) => (local_part.to_string(), Some(domain.to_string())),
		None => (s.to_string(), None),
	}
}

#[cfg(test)]
mod tests {
	use super::{CodedAddress, KeyedAddress};
	use std::str::FromStr;

	#[test]
	fn parse_coded_addr_empty_email() {
		assert!(CodedAddress::parse("", '+').is_err());
	}

	#[test]
	fn parse_coded_addr_empty_local() {
		assert!(CodedAddress::parse("@example.com", '+').is_err());
	}

	#[test]
	fn parse_coded_addr_empty_domain() {
		assert!(CodedAddress::parse("derp@", '+').is_err());
	}

	#[test]
	fn parse_keyed_addr_empty_email() {
		assert!(KeyedAddress::from_str("").is_err());
	}

	#[test]
	fn parse_keyed_addr_empty_local() {
		assert!(KeyedAddress::from_str("@example.com").is_err());
	}

	#[test]
	fn parse_keyed_addr_empty_domain() {
		assert!(KeyedAddress::from_str("derp@").is_err());
	}

	#[test]
	fn parse_keyed_addr_invalid_key_length() {
		assert!(KeyedAddress::from_str("test:bAXk1r7mgJY=").is_err());
	}

	#[test]
	fn parse_valid_coded_addr_with_domain() {
		let addr_str = "a+test+orsxg5a@example.org";
		let addr = CodedAddress::parse(addr_str, '+');
		assert!(addr.is_ok(), "unable to parse {addr_str}: {addr:?}");
		let addr = addr.unwrap();
		assert_eq!(addr.local_part, "a");
		assert_eq!(addr.sub_addr, Some("test".to_string()));
		assert_eq!(addr.code, b"test");
		assert_eq!(addr.domain, Some("example.org".to_string()));
	}

	#[test]
	fn parse_valid_coded_addr_with_invalid_base32() {
		let addr_str = "a+test+invalid@example.org";
		let addr = CodedAddress::parse(addr_str, '+');
		assert!(addr.is_ok(), "unable to parse {addr_str}: {addr:?}");
		let addr = addr.unwrap();
		assert_eq!(addr.local_part, "a");
		assert_eq!(addr.sub_addr, Some("test".to_string()));
		assert_eq!(addr.code, Vec::new());
		assert_eq!(addr.domain, Some("example.org".to_string()));
	}

	#[test]
	fn parse_valid_coded_addr_without_domain() {
		let addr_str = "local.part+test+orsxg5a";
		let addr = CodedAddress::parse(addr_str, '+');
		assert!(addr.is_ok(), "unable to parse {addr_str}: {addr:?}");
		let addr = addr.unwrap();
		assert_eq!(addr.local_part, "local.part");
		assert_eq!(addr.sub_addr, Some("test".to_string()));
		assert_eq!(addr.code, b"test");
		assert!(addr.domain.is_none());
	}

	#[test]
	fn parse_valid_coded_addr_alt_sep() {
		let addr_str = "local-part.test.orsxg5a@example.org";
		let addr = CodedAddress::parse(addr_str, '.');
		assert!(addr.is_ok(), "unable to parse {addr_str}: {addr:?}");
		let addr = addr.unwrap();
		assert_eq!(addr.local_part, "local-part");
		assert_eq!(addr.sub_addr, Some("test".to_string()));
		assert_eq!(addr.code, b"test");
		assert_eq!(addr.domain, Some("example.org".to_string()));
	}

	#[test]
	fn parse_valid_coded_addr_without_sub_addr() {
		let addr_str = "local.part@example.org";
		let addr = CodedAddress::parse(addr_str, '+');
		assert!(addr.is_ok(), "unable to parse {addr_str}: {addr:?}");
		let addr = addr.unwrap();
		assert_eq!(addr.local_part, "local.part");
		assert!(addr.sub_addr.is_none());
		assert!(addr.code.is_empty());
		assert_eq!(addr.domain, Some("example.org".to_string()));
	}

	#[test]
	fn parse_valid_keyed_addr_with_domain() {
		let addr_str = "a@example.org:11voiefK5PgCX5F1TTcuoQ==";
		let addr = KeyedAddress::from_str(addr_str);
		assert!(addr.is_ok(), "unable to parse {addr_str}: {addr:?}");
		let addr = addr.unwrap();
		assert_eq!(addr.local_part, "a");
		assert_eq!(addr.domain, Some("example.org".to_string()));
		assert_eq!(
			addr.key,
			vec![
				0xd7, 0x5b, 0xe8, 0x89, 0xe7, 0xca, 0xe4, 0xf8, 0x02, 0x5f, 0x91, 0x75, 0x4d, 0x37,
				0x2e, 0xa1
			]
		);
	}

	#[test]
	fn parse_valid_keyed_addr_without_domain() {
		let addr_str = "local.part:sbW22xNStWKro4nnMKmG3A==";
		let addr = KeyedAddress::from_str(addr_str);
		assert!(addr.is_ok(), "unable to parse {addr_str}: {addr:?}");
		let addr = addr.unwrap();
		assert_eq!(addr.local_part, "local.part");
		assert_eq!(addr.domain, None);
		assert_eq!(
			addr.key,
			vec![
				0xb1, 0xb5, 0xb6, 0xdb, 0x13, 0x52, 0xb5, 0x62, 0xab, 0xa3, 0x89, 0xe7, 0x30, 0xa9,
				0x86, 0xdc
			]
		);
	}

	#[test]
	fn keyed_addr_empty_address() {
		let res = KeyedAddress::from_str("");
		assert!(res.is_err());
	}

	#[test]
	fn keyed_addr_empty_base64() {
		let res = KeyedAddress::from_str("a:");
		assert!(res.is_err());
	}

	#[test]
	fn keyed_addr_invalid_base64() {
		let res = KeyedAddress::from_str("a:uh2kv%j3");
		assert!(res.is_err());
	}

	#[test]
	fn cmp_coded_addr_with_domain_eq() {
		let addr_1 = CodedAddress::parse("test+test+orsxg5a@example.org", '+').unwrap();
		let addr_2 = CodedAddress::parse("test+test+orsxg5a@example.org", '+').unwrap();
		assert_eq!(addr_1, addr_2);
	}

	#[test]
	fn cmp_coded_addr_without_domain_eq() {
		let addr_1 = CodedAddress::parse("test+test+orsxg5a", '+').unwrap();
		let addr_2 = CodedAddress::parse("test+test+orsxg5a", '+').unwrap();
		assert_eq!(addr_1, addr_2);
	}

	#[test]
	fn cmp_coded_addr_with_domain_ne() {
		let addr_1 = CodedAddress::parse("test+test+orsxg5a@example.org", '+').unwrap();
		let addr_2 = CodedAddress::parse("test2+test+orsxg5a@example.org", '+').unwrap();
		assert_ne!(addr_1, addr_2);
	}

	#[test]
	fn cmp_coded_addr_without_domain_ne() {
		let addr_1 = CodedAddress::parse("test+test+orsxg5a", '+').unwrap();
		let addr_2 = CodedAddress::parse("test2+test+orsxg5a", '+').unwrap();
		assert_ne!(addr_1, addr_2);
	}

	#[test]
	fn cmp_keyed_addr_with_domain_eq() {
		let addr_1 =
			KeyedAddress::from_str("test@example.org:gkJfLlKa2OLYItm4JD6p3hEF1kWH8LFtMK0rra8A2SQ=")
				.unwrap();
		let addr_2 = KeyedAddress::from_str("test@example.org:11voiefK5PgCX5F1TTcuoQ==").unwrap();
		assert_eq!(addr_1, addr_2);
	}

	#[test]
	fn cmp_keyed_addr_without_domain_eq() {
		let addr_1 =
			KeyedAddress::from_str("test:gkJfLlKa2OLYItm4JD6p3hEF1kWH8LFtMK0rra8A2SQ=").unwrap();
		let addr_2 = KeyedAddress::from_str("test:11voiefK5PgCX5F1TTcuoQ==").unwrap();
		assert_eq!(addr_1, addr_2);
	}

	#[test]
	fn cmp_keyed_addr_with_domain_ne() {
		let addr_1 = KeyedAddress::from_str("test@example.org:sbW22xNStWKro4nnMKmG3A==").unwrap();
		let addr_2 = KeyedAddress::from_str("test2@example.org:sbW22xNStWKro4nnMKmG3A==").unwrap();
		assert_ne!(addr_1, addr_2);
	}

	#[test]
	fn cmp_keyed_addr_without_domain_ne() {
		let addr_1 =
			KeyedAddress::from_str("test:gkJfLlKa2OLYItm4JD6p3hEF1kWH8LFtMK0rra8A2SQ=").unwrap();
		let addr_2 =
			KeyedAddress::from_str("test2:gkJfLlKa2OLYItm4JD6p3hEF1kWH8LFtMK0rra8A2SQ=").unwrap();
		assert_ne!(addr_1, addr_2);
	}

	#[test]
	fn cmp_addr_types_with_domain_eq() {
		let addr_1 = KeyedAddress::from_str("test@example.org:sbW22xNStWKro4nnMKmG3A==").unwrap();
		let addr_2 = CodedAddress::parse("test+test+orsxg5a@example.org", '+').unwrap();
		assert_eq!(addr_1, addr_2);
	}

	#[test]
	fn cmp_addr_types_without_domain_eq() {
		let addr_1 = KeyedAddress::from_str("test:sbW22xNStWKro4nnMKmG3A==").unwrap();
		let addr_2 = CodedAddress::parse("test+test+orsxg5a", '+').unwrap();
		assert_eq!(addr_1, addr_2);
	}

	#[test]
	fn cmp_addr_types_without_sub_addr() {
		let addr_1 = KeyedAddress::from_str("test@example.org:sbW22xNStWKro4nnMKmG3A==").unwrap();
		let addr_2 = CodedAddress::parse("test@example.org", '+').unwrap();
		assert_eq!(addr_1, addr_2);
	}

	#[test]
	fn cmp_addr_types_idna_1() {
		let addr_1 =
			KeyedAddress::from_str("test@mél.example.org:sbW22xNStWKro4nnMKmG3A==").unwrap();
		let addr_2 = CodedAddress::parse("test@xn--ml-bja.example.org", '+').unwrap();
		assert_eq!(addr_1, addr_2);
	}

	#[test]
	fn cmp_addr_types_idna_2() {
		let addr_1 =
			KeyedAddress::from_str("test@xn--ml-bja.example.org:sbW22xNStWKro4nnMKmG3A==").unwrap();
		let addr_2 = CodedAddress::parse("test@mél.example.org", '+').unwrap();
		assert_eq!(addr_1, addr_2);
	}

	#[test]
	fn cmp_addr_types_with_domain_ne() {
		let addr_1 = KeyedAddress::from_str("test@example.org:sbW22xNStWKro4nnMKmG3A==").unwrap();
		let addr_2 = CodedAddress::parse("test+test+orsxg5a@example.com", '+').unwrap();
		assert_ne!(addr_1, addr_2);
	}

	#[test]
	fn cmp_addr_types_without_domain_ne() {
		let addr_1 = KeyedAddress::from_str("test:sbW22xNStWKro4nnMKmG3A==").unwrap();
		let addr_2 = CodedAddress::parse("test2+test+orsxg5a", '+').unwrap();
		assert_ne!(addr_1, addr_2);
	}
}